1. Field of the Invention
The invention relates to an apparatus that is inserted into a lumen such as a blood vessel, urethra or abdominal cavity to irradiate a tissue with an energy such as a laser ray or an ultrasonic ray that is capable of reaching deep into the tissue.
2. Description of the Related Art
It is well known that an energy irradiation apparatus of a long shape that can be inserted into the body utilizing a celom or a small incision is useful for irradiating a lesional region to reduce or to eliminate it through alteration, necrosis, coagulation, cauterization or evaporation for the treatment.
The technique in general is to irradiate directly a lesional region located at a surface layer of a tissue or its proximity. There is another technique of irradiating a tissue with a purpose of curing of a lesional region located deep in the tissue, or a deep lesional region. However, in order to reduce or to eliminate a tissue of the deep lesional region, it requires a relatively strong energy, which may cause a damage to the surface layer.
U.S. Pat. Nos. 5,292,320 and 5,496,308 disclose irradiation apparatuses for curing Benign Prostatic Hyperplasia by means of a laser ray as an irradiating energy. In the irradiation apparatuses, laser rays radiated from a plurality of irradiating units located at different positions converge on a target point in the deep lesional region to generate a sufficient amount of heat to reduce or to eliminate the ailing tissue. Thus, the temperature becomes higher than those of other areas where laser rays are not concentrated. However, since the paths of the laser rays are fixed, the temperature of a surface layer and its proximity where laser rays are not overlapped becomes relatively higher than those of other areas where any laser rays are not transmitted. This phenomenon affects the protection of the surface layer. Therefore, it is circumstantially difficult to heat the deep lesional region to a temperature necessary for reducing or removing the tissue of the deep lesional region while minimizing damages to the surface layer.
Also known is the leksell gamma knife, an apparatus used for the treatment of encephalic diseases utilizing gamma ray as a source of irradiating energy. In the apparatus, gamma rays radiated simultaneously from a plurality of irradiating units arranged in a semispherical pattern converge on a target point in the deep lesional region to bring a necrosis to the ailing tissue. However, the gamma rays also affect tissues existing along the paths of the rays as the rays pass through. Therefore, it is circumstantially difficult with such an apparatus to reduce or to remove the ailing tissue in the deep lesional region while minimizing the damages to the surface layer, also.
An object of the invention is to provide an apparatus that is capable of effectively radiating an energy to a target region, particularly a region located in a deep area, while easily and securely preventing damages to a normal tissue, particularly a normal tissue in the surface layer.
Another object of the invention is to provide a method of treating Benign Prostatic Hyperplasia, while easily and securely preventing damages to a normal tissue, particularly a normal tissue in the surface layer.
One aspect of the invention is an energy irradiation apparatus includes an irradiating unit, a transporting device and an interlocking device. The irradiating unit radiates an energy with a deep transmitting capability against a tissue. The transporting device transports the irradiating unit within a predetermined area. The interlocking device changes irradiation angle in response to transportation of the irradiating unit so that the energy radiated by the moving irradiating unit always passes through an area which is smaller than the predetermined area.
Another aspect of the invention is a treatment method for Benign Prostatic Hyperplasia by irradiating a first area existing in a lesional region of prostate while moving an irradiating unit for radiating laser ray with a deep transmitting capability against a tissue within a second area which is larger than the first area and changing irradiating angle of the laser ray in correspondence to motion of the irradiating unit.
The objects, characteristics, and advantages of this invention other than those set forth above will become apparent from the following detailed description of the preferred embodiments, which refers to the annexed drawings.